C++ overloaded operator with reverse order of associativity -

it hard come title... (i'm not native english speaker.)

struct {     int value;     operator+(int i) const     {         a;         a.value=value+i;         return a;     }; }; int main(){     a;     a.value=2;     a=a+2;     return 0; } 

this code compiles/works expected, when change a=a+2 a=2+a, won't compile anymore. gcc gives me error:

no match ”operator+” in ”2 + a” 

is there way somehow make 2+a work a+2?

you need free function, defined after class

struct {    // ... };  operator+(int i, const a& a) {   return a+i; // assuming commutativity }; 

also, might consider defining a& operator+=(int i); in a implement both versions of operator+ free functions. might interested in boost.operators or other helpers simplify a, see profile 2 options.